CONCEPT cars make the headlines at the world's motor shows - and then sadly often disappear into obscurity.

For the manufacturer they represent a shop window, a laboratory on wheels and a test bench for new ideas among customers.

And for those who can read the signs they often reveal the manufacturer's vision of the shape of things to come.

If you are a motor show visitor you can look around them on the stands and if you are lucky sit in them. But drive them? Forget it!

At least that is normally the case.

Peugeot, however, decided its concept cars were too good to be hidden away and invited myself and two other UK motoring journalists to get behind the wheel of some of the most stunning - and in some cases bizarre - cars its designers have ever penned.

To drive this Aladdin's cave of motoring glitterati I had to travel to Mortefontaine, the French motor industry's proving ground near Paris.

It was a journey, however, that proved to be well worthwhile, especially as it allowed me to take to the road in the stunning new RC Z , Peugeot's answer to the Audi TT and a car not due for production until 2010.

And when I say the RC Z I mean the RC Z. There is only one at present.

Which was why I asked the Peugeot employee who accompanied me on the test drive how much it was worth - and then wished I hadn't when he casually put a £1 million price tag on it.

I made a mental note to be extra careful with the RC Z. The French car giant would be decidedly unhappy if I bent it.

When the car finally comes into UK showrooms in two years time it will fulfil the desires of those motorists who always wanted an Audi TT but found the price tag too high.

Despite the concept's value, normal production models are expected to sell for around £20,000.

In a slightly contradictory description Peugeot says the car, which is powered by a volume/niche vehicle.

It's a stunning 2+2 with muscular haunches, a clever wave shaped rear window and enough room in the luggage area to accommodate a mountain bike.

The beefy 1.6-litre engine mated to a six-speed gearbox gives plenty of grunt and pretty dynamic acceleration. Even though I was limited to how much I could push the car - being a concept - it was obvious there was far more to come.

On a series of flowing bends the RC Z sat squat and flat almost oblivious to the changes in the road's contours. Audi owners will be impressed.

Next up was the RC Diamond which - together with the RC Spades - made the headlines at the Geneva Motor Show of 2003.

The playing card twins look like baby Lamborghinis and would certainly stop the traffic if they were allowed onto any public highway.

These two cars are the stuff of James Bond films, with their gullwing doors and mid-engined construction.

As concept cars they don't come with the niceties of production vehicles so there is no power steering and no servo-assisted brakes.

Nevertheless, for any enthusiast they are an absolute delight to drive and had Peugeot ever gone into serious production I would have put one on my wish list.

The Diamond is powered by a 2.2-litre HDi diesel engine and uses a six-speed tiptronic style gearbox.

It was fortunate there was no clutch as the driver's seat had jammed and I could just about reach the accelerator and brake.

Despite their diminutive dimensions the Diamond and Spades - the latter uses a 2.0-litre petrol engine - are four seaters.

After the glamour it was time for something a little more unusual; Peugeot's version of the "push me pull you" better known as the Hoggar.

This whacky moon buggy type vehicle has two engines, one at the front to pull you and one at the rear to push you.

Each engine drives its own axle to give a new meaning to four-wheel-drive.

A little bit of off-roading showed me how capable it was but I can't ever see it trundling down Broad Street.

By now I was up to £4 million on my calculator of cars driven but after that I had to be content with sampling the other concepts as a passenger. Peugeot obviously didn't want me to push my luck.

The Peugeot 907 concept was not designed for your average family motorist. With a huge 6.0-litre V12 under the bonnet and a transparent panel showing off all 12 chrome intake trumpets - reminiscent of a fairground organ - it's not for the faint-hearted.

But as a styling concept first seen at the 2004 Paris Motor Show it did herald a number of styling cues for future Peugeot models.

The long nose of the 500 bhp, carbon fibre 907 and its "facial expression" can now be seen on the current Peugeot 308.

To end my visit I was given a ride in the 20Cup, an open topped wacky cross between the world of the car and the motorbike, with two wheels at the front and one at the rear.

The light construction and low centre of gravity - you sit virtually on the floor and have to climb in as there are no doors - ensures an exhilerating if somewhat raw ride in this turbocharged 1.6-litre, 170 bhp three wheeler. Del Boy eat your heart out.

There was one other concept I was shown, the stunningly beautiful 908 RC limousine.

But as this is powered by the 700 bhp V12 which powers the competition 908 Le Mans racer perhaps it was understandable that Peugeot thought it sensible just to let me drool over it rather than drive it.